Scanner for industrial laser machines

ABSTRACT

A scanner for industrial laser machines, which comprises a housing (1)  acmodating a movable scanning element (4) a means (12) for inducing mechanical oscillations of the scanning element (4), which is mechanically connected to the housing (1), and a measuring transducer (19) responding to the mechanical oscillations of the scanning element (4). At least two collision pairs (5) are connected with the housing (1) and the scanning element (4). The measuring transducer (19) is connected to a phase shift unit (21) coupled to a saturation unit (24). The means (12) for inducing mechanical oscillations of the scanning element (4) and the saturation unit (24) are connected to a power amplifier (27).

TECHNICAL FIELD

This invention relates to scanners and, more specifically, to scannersfor industrial laser machines.

BACKGROUND ART

Modern machine building industry demands that machine components aremade more durable and resistant to wear. At present, one of the mostpromising methods for hardening work-pieces to make them more resistantto wear is laser heat treatment of workpiece surfaces. Scanning systemsemployed for such purposes in industrial lasers are the basic devicescontrolling the laser beam in order to ensure high quality andefficiency of laser treatment.

Known in the art is a scanner for industrial lasers (cf., French PatentApplication No. 8,509,169), comprising a housing accomodating a movablescanning member, a means for inducing mechanical oscillations of thescanning member, which is connected with the housing, and at least twocollision pairs, each such pair having two components secured so thatthey can interact with each other during displacements of the scanningmember, one component being placed on the scanning member and the otherin the housing.

However, this scanner is deficient in that, in order to reduce theeffect of parameter fluctuations of the means for inducing mechanicaloscillations and the scanning member on the operational conditions ofthe scanner, the speed of scanning is deliberately brought down. If thescanning speed is increased, the collision mode of operation can beupset and the scanner starts to operate in a collision-free mode at alow scanning speed and amplitude. In other words, the operation of thescanner is totally disturbed.

Besides, the deliberate reduction of the scanning speed in this scannerresults in a lower collision speed of components of collision pairs.This leads to deviation from the desired optimal (sawtooth) scanning lawand deterioration of the scanning accuracy.

DISCLOSURE OF THE INVENTION

It is an object of this invention to provide a scanner for industriallaser machines, which is equipped with such additional units as toincrease the speed of collisions in collision pairs without increasingthe power of the means for inducing mechanical oscillations of thescanning element, and also to raise the accuracy of scanning.

This is achieved in that a scanner for industrial laser machines,comprising a housing accomodating a movable scanning element, a meansfor inducing mechanical oscillations of the scanning element, which ismechanically secured to the housing, at least two collision pairs, eachpair having two components secured so that they can interact with eachother during the movement of the scanning element, one component beingsecured on the scanning element and the other in the housing, accordingto the invention, additionally comprises a measuring transducer whichresponds to mechanical oscillations of the scanning element, a phaseshift unit whose input is connected to the measuring transducer, asaturation unit whose input is connected to an output of the phase shiftunit, and a power amplifier whose input is connected to the saturationunit and whose output is connected to the means for inducing mechanicaloscillations of the scanning member.

Advisably, the scanner for industrial laser machines should additionallycomprise a frequency meter connected to the output of the phase shiftunit and a saturation level control unit coupled to the frequency meter,while the saturation unit should feature at least two control inputsconnected to respective outputs of the saturation level control unit.

Desirably, in the scanner for industrial laser machines, the saturationlevel control unit should comprise a division unit whose one input isthe input of the saturation level control unit, while the other inputthereof is connected to a constant voltage source, inverting andnoninverting direct-coupled amplifiers, the input of each direct-coupledamplifier being connected to an output of the division unit, while theoutput of each such direct-coupled amplifier is the respective output ofthe saturation level control unit.

Reasonably, the scanner for industrial laser machines shouldadditionally comprise a periodic signal generator whose output is joinedwith the output of the saturation unit and connected to the input of thepower amplifier.

It is also advisable that in the scanner for industrial laser machinesthe phase shift unit should comprise a component selected from a groupcomprising a phase shifter, a corrector circuit, and a filter in thisorder, individually or in combination.

It is also desirable that in the scanner for industrial laser machinesthe phase shift unit should comprise a phase shifter and a correctioncircuit connected in series to each other.

It is also reasonable that in the scanner for industrial laser machinesthe phase shift unit should comprise a phase shifter and a filterconnected in series.

Besides, it is advisable that in the scanner for industrial lasermachines the phase shift unit should comprise a correction circuit and afilter connected in series.

Besides, it is desirable that in the scanner for industrial lasermachines the phase shift unit should comprise a phase shifter, acorrection circuit, and a filter connected in series to one another.

Besides, it is reasonable that in the scanner for industrial lasermachines the phase shift unit should additionally have at least twocontrol inputs, and the scanner should additionally comprise a phaseshift control means having outputs whose number is equal to that of thecontrol inputs of the phase shift unit, each output being connected to arespective input of the phase shift unit.

Possibly, in the scanner for industrial laser machines the phase shiftershould have two control inputs, each input being connected to arespective output of the phase shift control means.

It is also possible that in the scanner for industrial laser machinesthe correction circuit should have four control inputs, each controlinput being connected to a respective output of the phase shift controlmeans.

In addition, it is possible that in the scanner for industrial lasermachines the filter should have four control inputs, each control inputbeing connected to a respective output of the phase shift control means.

Preferably, in the scanner for industrial laser machines, the phaseshift control means should be a microprocessor.

This invention is used to achieve a higher frequency of scanning and,consequently, a higher speed of scanning.

Besides, this invention is used to provide operational scanningconditions on the basis of an optimal (sawtooth) scanning law, which canimprove the accuracy of scanning.

This invention can also provide stable free-running operation of thescanner, which improves its noise immunity and prevents disruption ofthe scanner operational mode, thus improving the reliability of thescanner.

This invention can also realize an automatic process of bringing thescanner to the optimal operational mode of scanning.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

Other objects and advantages of this invention will become more apparentfrom the following detailed description of preferred embodimentsthereof, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a functional diagram of a scanner for industrial lasermachines, according to the invention;

FIG. 2 shows a functional diagram of a scanner for industrial lasermachines of FIG. 1 featuring a phase control mens, according to theinvention;

FIG. 3 shows functional diagram of a scanner for industrial lasermachines of FIG. 2 featuring a frequency meter, according to theinvention;

FIG. 4 shows a functional block diagram for industrial laser machines ofFIG. 2 featuring a periodic signal generator, according to theinvention;

FIG. 5 shows a functional block diagram of a phase shifter, according tothe invention;

FIG. 6 shows a functional block diagram of a correction circuit,according to the invention;

FIG. 7 shows a functional block diagram of a filter, according to theinvention;

FIG. 8 shows a functional block diagram of a phase shift unit featuringa phase shifter and a correction circuit, according to the invention;

FIG. 9 shows a functional block diagram of a phase shift unit featuringa phase shifter and a filter, according to the invention;

FIG. 10 shows a functional block diagram of a phase shift unit featuringa correction circuit and a filter, according to the invention;

FIG. 11 shows a functional block diagram of a phase shift unit featuringa phase shifter, a correction circuit, and a filter, according to theinvention;

FIG. 12 shows a functional block diagram of a phase shifter of FIG. 5featuring control inputs, according to the invention;

FIG. 13 shows a functional block diagram of a correction circuit of FIG.6 featuring control inputs, according to the invention;

FIG. 14 shows a functional block diagram of a filter of FIG. 7 featuringcontrol inputs, according to the invention;

FIG. 15 shows a functional block diagram of a phase shift unit as shownin FIG. 8 featuring control inputs, according to the invention;

FIG. 16 shows a functional block diagram of a phase shift unit as shownin FIG. 9 featuring control inputs, according to the invention;

FIG. 17 shows a functional block diagram of a phase shift unit as shownin FIG. 10 featuring control inputs, according to the invention;

FIG. 18 shows a functional block diagram of a phase shift unit as shownin FIG. 11 featuring control inputs, according to the invention;

FIG. 19 shows a functional block diagram of a saturation level controlunit as shown in FIG. 3, according to the invention;

FIG. 20 shows a schematic diagram of a saturation unit;

FIG. 21 shows a plot of the output voltage of the saturation unit as afunction of the input voltage thereof;

FIG. 22 shows an amplitude-frequency characteristic of the scanner forindustrial laser machines.

BEST MODE FOR CARRYING OUT THE INVENTION

The scanner for industrial laser machines described herein below by wayof example makes use of an electromechanical method of excitingoscillations.

A scanner for industrial laser machines comprises a housing 1 (FIG. 1)accomodating a rocker 2 on a shaft 3 about which the rocker 2 can tilt.The rocker 2 carries a scanning element made as a mirror 4. Identicalcollision pairs 5 are placed symmetrically in relation to the shaft 3 ofthe rocker 2. Each collision pair 5 comprises a first component 6installed on a respective arm of the rocker 2 in the immediate vicinityof its butt end 7, and a second component 8 installed in the housing 1so that it can interact with the component 6 when the mirror 4 moves.The second component 8 can be adjusted by means of a screw 9. Resilientmembers made as springs 11 are arranged symmetrically to the geometricalaxis 10 of the scanner below the rocker 2. The springs 11 connect therocker 2 to the housing 1. A means 12 for inducing mechanicaloscillations of the scanning element is placed in the housing 1 beneaththe rocker 2. The means 12 comprises two identical electromagnets 13 and14 equipped with respective windings 15 and 16. The winding 15 isconnected to the cathode of a control diode 17, while the winding 16 isconnected to the anode of a control diode 18. A measuring transducerdisposed beneath the rocker 2 can be made, for example, as a knownphotoelectric displacement transducer 19. An output 20 of thedisplacement transducer 19 is connected to an input 22 of a phase shiftunit 21 whose output 23 is connected to an input 25 of a saturation unit24 (cf., for example, V. A. Besekersky, E. P. Popov, Theory of AutomaticControl Systems, Moscow, 1972, Nauka Publ., p. 548). An output 26 of thesaturation unit 24 is connected to a power amplifier 27 whose output 28is connected to the anode of the diode 17 and to the cathode of thediode 18.

The scanner is equipped with a phase shift control means for preliminaryadjustment to the maximum oscillation frequency. This phase shiftcontrol means may be a known microprocessor 29 (FIG. 2) whose outputs 30and 31 are connected, respectively, to control inputs 32 and 33 of thephase shift unit 21.

Another embodiment of the scanner for industrial laser machinesadditionally comprises a frequency meter 34 (FIG. 3) whose input 35 isconnected to the output 23 of the phase shift unit 21 and a saturationlevel control unit 36 whose input 37 is connected to the frequency meter34. Outputs 38 and 39 of the saturation level control unit 36 areconnected to respective inputs 40 and 41 of the saturation unit 24.

Still another embodiment of the scanner for industrial laser machinesadditionally comprises a periodic signal generator 42 (FIG. 4) whoseoutput 43 is joined with the output 26 of the saturation unit 24 in apoint 44 and coupled to the amplifier 27.

One embodiment of the phase shift unit is a phase shifter 45 (FIG. 5)comprising a subtraction means 46 whose input 47 is connected to adifferentiation means 48.

Inputs 49 and 50 of the means 46 and 48, respectively, are joined in aconnection point 51 and constitute the input of the phase shifter 45which is the input 22 (FIG. 1) of the phase shift unit 21. The output ofthe subtraction means 46 (FIG. 5) is connected to an input 53 of a firstorder aperiodic circuit 52. The output of the aperiodic circuit 52 isthe output of the phase shifter 45, which is the output 23 (FIG. 1) ofthe unit 21.

Another embodiment of the phase shift unit is a correction circuit 54(FIG. 6) comprising two addition means 55 and 56 whose inputs 57 and 58are respectively connected to differentiation means 59 and 60. Inputs 61and 62 of the means 55 and 59, respectively, are joined together andconstitute an input of the correction circuit 54, which is the input 22(FIG. 1) of the unit 21. Inputs 63 and 64 of the means 56 and 60,respectively, are joined together and connected to the means 55. Aninput 65 of a first order aperiodic circuit 66 is connected to the means55. The output of the aperiodic circuit 66 is connected to an input 67of another first order aperiodic circuit 68 whose output is the outputof the correction circuit 54, which is the output 23 (FIGS. 2 and 1) ofthe unit 21.

Another embodiment of the phase shift unit 21 is a filter 69 (FIG. 7)comprising series-connected differentiation means 70 and 71. The outputof the differentiation means 71 is connected to an input 73 of thedifferentiation means 72. Inputs 74 and 75 of the means 70 and 72,respectively, are joined in a connection point 76 and constitute theinput of the filter 69, which is the input 22 (FIG. 1) of the phaseshift unit 21. The differentiation means 72 is connected to an input 77of a first order aperiodic circuit 78 whose output is connected to aninput 79 of another first order aperiodic circuit 80. The output of theaperiodic circuit 80 is the output of the filter 69, which is the output23 (FIG. 1) of the unit 21.

Still another embodiment of the phase shift unit 21 comprises aseries-connected phase shifter 45 (FIG. 8) whose input is the input 22(FIG. 1) of the phase shift unit 21 and a correction circuit 54 (FIG. 8)whose output is the output 23 (FIG. 1) of the unit 21.

One more embodiment of the phase shift unit 21 comprises aseries-connected phase shifter 45 (FIG. 9) whose input is the input 22(FIG. 1) of the phase shift unit 21 and a filter 69 (FIG. 9) whoseoutput is the output 23 (FIG. 1) of the phase shift unit 21.

Still one more embodiment of the phase shift unit 21 comprises acorrection circuit 54 (FIG. 10) whose input is the input 22 (FIG. 1) ofthe phase shift unit 21 and the filter 69 (FIG. 10) connected in seriesto the correction circuit 54, whose output is the output 23 (FIG. 1) ofthe phase shift unit 21.

Yet another embodiment of the phase shift unit 21 comprises aseries-connected chain including the phase shifter 45 (FIG. 11) whoseinput is the input 22 (FIG. 1) of the phase shift unit 21, thecorrection circuit 54 (FIG. 11), and the filter 69 whose output is theoutput 23 (FIG. 1) of the phase shift unit 21.

Referring to FIG. 12, an embodiment of the phase shift unit 21 (FIGS. 2,3, 4) comprises a phase shifter 45 (FIG. 5) wherein the means 48 andaperiodic circuit 52 are provided with control inputs which are controlinputs 81 and 82 (FIG. 12) of the phase shifter 45 and, respectively,the control inputs 32 and 33 (FIGS. 2, 3, 4) of the unit 21.

Referring to FIG. 13, an embodiment of the phase shift unit 21 is acorrection circuit 54 (FIG. 6) wherein the means 59 and 60 and aperiodiccircuits 66 and 68 are provided with control inputs which are,respectively, control inputs 83,84, 85, and 86 (FIG. 13) of theaperiodic circuit 54 and, consequently, of the phase shift unit 21 (notshown).

Referring to FIG. 14, an embodiment of the phase shift unit 21 is afilter 69 (FIG. 7) wherein the means 70 and 71 and circuits 78 and 80are provided with control inputs which are control inputs 87, 88, 89,and 90 (FIG. 19) and, consequently, of the unit 21 (not shown).

Referring to FIG. 15, an embodiment of the phase shift unit 21 isanalogous to that of FIG. 8 with one exception consisting in that theunit 21 is provided with control inputs which are the inputs 81 and 82of the phase shifter 45 and inputs 83, 84, 85, and 86 of the correctioncircuit 54.

Referring to FIG. 16, an embodiment of the phase shift unit 21 isanalogous to that of FIG. 9 with one exception consisting in that thephase shift unit 21 is provided with control inputs which are the inputs81 and 82 of the phase shifter 45 and inputs 87, 88, 89, and 90 of thefilter 69.

Referring to FIG. 17, an embodiment of the phase shift unit 21 isanalogous to that shown in FIG. 10 with the exception consisting in thatthe phase shift unit 21 is provided with control inputs which are theinputs 83, 84, 85, and 86 of the correction circuit 54 and inputs87,88,89, and 90 of the filter 69.

Referring to FIG. 18, an embodiment of the phase shift unit 21 isanalogous to that shown in FIG. 11 with an exception consisting in thatthe phase shift unit 21 is provided with control inputs which are theinputs 81 and 82 of the filter 45, inputs 83,84,85, and 86 of thecorrection circuit 54, and inputs 87,88,89, and 90 of the filter 69.

The saturation level control unit 36 (FIG. 3) comprises a division unit31 whose one input is the input 37 of the saturation level control unit36, while another input 92 is connected to a constant voltage source 93.The output of the division unit 91 is connected to inputs 94 and 95 ofthe inverting and noninverting amplifiers 96 and 97, respectively. Theoutputs of the amplifiers 96 and 97 are, respectively, the outputs 38and 39 of the unit 36.

The known saturation unit 24 (V. A. Besekersky, E. P. Popov, Theory ofAutomatic Control Systems, Moscow, 1972, NAUKA Publ., p. 196) comprisesa resistor 98 (FIG. 20) whose one lead is the input 25 of the saturationunit 24, while the other lead is connected to the cathode of a diode 99,the anode of a diode 100, a lead of a resistor 101, and an invertinginput 102 of an operational amplifier 103 in a connection point 104. Theother input of the operational amplifier 103 is grounded. The other leadof the resistor 101, an output 105 of the operational amplifier 103, andsome leads of tandem variable resistors 106 and 107 are joined in aconnection point 108 which is the output 26 of the saturation unit 24.Other leads of the resistors 106 and 107 are, respectively, the controlinputs 40 (FIG. 3) and 41 of the saturation unit 24. Current collectors109 and 110 of the resistors 106 and 107, respectively, are connected tothe cathode of the diode 100 and to the anode of the diode 99,respectively.

The scanner for industrial lasers, as shown in FIGS. 1,21, and 22,operates as follows.

Conventionally, the operation of a scanner for industrial laser machinesconsists in that a mirror periodically deflects the laser beam of apowerful industrial laser (not shown in the drawings). The deflectedbeam is directed to a workpiece to be laser treated.

The angular displacement of the mirror 4 is sensed by the photoelectrictransducer 19 and converted into an electric signal proportional to theangle to which the mirror 4 is turned. The signal is further deliveredfrom the output 20 of the transducer 19 to the input 22 of the phaseshift unit 21 which changes the phase of the signal and supplied it fromthe output 23 thereof to the input 25 of the saturation unit 24.

When the voltage amplitude at the input 25 (FIG. 1) of the saturationunit 24 is low u<u₁ (as shown in FIG. 21), which is typical for aprocess leading to steady-state mechanical oscillation conditions, thevoltage U at the output 26 of the saturation unit 24 is increased by afactor of k (where k+tgα and α is the slope of the curve U(u) in FIG.21).

When the amplitude of the voltage u>u₁, the amplitude of the voltage Uremains constant and equal to the saturation level U₁ (shown in FIG.21). Then, the voltage at the output 26 of the unit 24 is equal U=U₁ orU=-U₁. The signal taken from the output 26 of the saturation unit 24 issupplied to the power amplifier 27. The amplified signal from the output28 of the power amplifier 27 is fed to the electromagnets 13 and 14 ofthe means 12 for inducing mechanical oscillations in order to set therocker 2 and the mirror 4 in motion.

In this manner the scanner is self-excited and reaches stationaryoptimal (sawtooth) conditions of scanning of the mirror 4 with thefrequency f₁ (FIG. 22) and amplitude a₁ (FIG. 22) of the angulardisplacements, which correspond to the point 111 (FIG. 22) on theamplitude-frequency curve of the scanner. In these conditions,fluctuations of scanner parameters, such as supply voltage of theelectromagnets 13 and 14, for example, do not upset the optimaloperating conditions to a collision-free harmonic mode of operation withthe amplitude a₂ (f₂), which corresponds to the point 112 (FIG. 22).

When the scanner is readjusted to a different scanning frequency, thephase shift may have to be altered in order to reach again the optimaloperating conditions. To this end, signals are to be applied from theoutputs 30

(FIG. 2) and 31 of the microprocessor 29 to respective control inputs 32and 33 of the unit 21 and change the phase shift by a required value.

The scanner for industrial laser machines, as shown in FIGS. 3, 19, 20,21, and 22, operates as follows.

Basically, the scanner operates similarly to the one described above.But, here the scanning frequency is stabilized to achieve a stablescanning speed. To this end, the signal taken from the output 23 of theunit 21 is also supplied to the input 35 of the frequency meter 34 to betransformed into a signal whose frequency is the function of theoscillation frequency of the mirror 4 and delivered to the input 37 ofthe saturation level control unit 36. The unit 36 produces controlsignals supplied from the outputs 38 and 39 thereof to the controlinputs 40 and 41 of the saturation unit 24. Both positive and negativesaturation levels U₁ and -U₁ are produced in the unit 24.

The saturation levels U₁ and -U₁ are produced in the unit 24 as follows.

The signal applied to the input 25 (FIG. 20) of the saturation unit 24is further supplied, via the resistor 98, to the inverting input 102 ofthe operational amplifier 103. The negative feedback voltage is alsosupplied to the input 102 of the operational amplifier 103 from theoutput 105 via the resistor 101. When the voltage amplitudes u<u₁ (FIG.21) at the input 25, current flows from the control input 40 via theresistors 106 and 107 to the control input 41 and produces potentials onthe current collectors 109 and 110, which render nonconductive diodes100 and 99, respectively. In this case, the gain factor of thesaturation unit 24 and the voltage U at its output 26 are dictated bythe ratings of the resistors 98 and 101. When the voltage amplitude u>u₁at the input 25 of the saturation unit 24, in other words, when the unit24 is in saturated condition, diodes 99 and 100 become conductive andfunish additional feedbacks for the amplifier 103, which reduce the gainfactor of the saturation unit 24 so that the positive and negativesaturation levels at the output 26 remain equal, respectively, to thelevels U₁ and -U₁ (FIG. 21).

The saturation levels U₁ and -U₁ are controlled as follows.

A signal of the frequency meter 34 is supplied to one input of thedivision unit 91, while a signal of the constant voltage source 93 issupplied to the input 92. The division unit 91 transforms these signalsinto a signal whose magnitude is equal to the ratio of the voltage atthe input 92 and the voltage applied to the input of the division unit91 from the frequency meter 34. The signal obtained in the division unit91 is supplied to the inputs 94 and 95 of the inverting and noninvertingamplifiers 96 and 97, respectively, where its magnitude is increased,and in the amplifier 96 the sign is also changed. The signal is thensupplied from the outputs of the amplifiers 96 and 97 to the controlinputs 40 and 41, respectively, of the saturation unit 24. Potentials atthe inputs 40 and 41 vary with the fluctuations of the scannerparameters, and so do potentials at the current collectors 109 and 110and the saturation levels U₁ and -U₁. When frequencies reach values f₃or f₄ (FIG. 22) which correspond to the points 113 and 114 (FIG. 22),the saturation levels U₁ and -U₁ change, respectively, to U₂, -U₂ andU₃, -U₃ (FIG. 22). The scanning frequency also changes and becomes closeto the desired frequency f₁.

The assigned scanning speed and respective oscillation frequency andamplitude can be adjusted by placing the current collectors 109 and 110of the resistors 106 and 107 to an appropriate position.

The scanner for industrial laser machines, as shown in FIGS. 4 and 22,operates as follows.

Basically, the operation of this scanner is similar to that of FIG. 1.But, the signal taken from the output 26 of the saturation unit 24 isadded to the signal taken from the output 43 of the periodic signalgenerator 42, which changes at the assigned scanning frequency. Themirror 4 oscillates with the frequency assigned by the generator 42,which is the manifestation of the well known effect of near-harmonicoscillations, when the frequency of the driving harmonic action "locksin" the free-running frequency. In contrast to the well known effect,the above fenomenon occurs during the saw-tooth movement law at afrequency f₁ (FIG. 22) which is much higher than the natural frequencyf₅ (FIG. 22) of the oscillatory system comprising the rocker 2 with themirror 4 and springs 11.

When a large phase shift is required in scanners for industrial lasermachines, as shown in FIGS. 1, 2, 3, 4, the signal of the transducer 19is supplied to the inputs 50 and 49 (FIG. 5) of the differentiationmeans 48 and the subtraction means 46 of the phase shifter 45,respectively. The means 48 differentiates the signal and changes itsmagnitude in compliance with its transmission function W(p)=Tp, wherep=d/dt is the differentiation operator and T is the time constant of themeans 48. The signal is further fed from the means 48 to the input 47 ofthe means 46 where it is subtracted from the signal which had beendelivered to the input 49.

The resulting signal is taken from the means 46 to the input 53 of thefirst order aperiodic circuit 52 whose transfer function is W(p)=k₁/(1+T₁ p), where k₁ is a constant factor, and T₁ is the time constant ofthe aperiodic circuit 52 equal to T so that T₁ =T. The aperiodic circuit52 changes the magnitude and phase of the signal and supplies it to theinput 25 of the saturation unit 24.

When the scanner is adjusted to another phase shift, as described above,signals taken from the outputs 30 (FIGS. 2, 3, 4) and 31 of themicroprocessor 29 are supplied to the inputs 81 (FIG. 12) and 82 of thephase shifter 45, that is to respective control inputs of the means 48and the aperiodic circuit 52, in order to change their time constants.The phase shift is thus changed by a required value.

When a small phase shift is required and phase shifts in theelectromagnets 13 and 14, the transducer 19, the saturation unit 24, andthe amplifier 27 are to be corrected at various desired scanningfrequencies in scanners for industrial laser machines of FIGS. 1, 2, 3,and 4, the signal taken from the transducer 19 is supplied to the inputs62 and 61 of the diffentiation means 59 and addition means 55 of thecorrection circuit 54 (FIG. 6). After differentiation in the means 59,the signal is supplied to the input 57 of the addition means 55 where itis added to the signal fed from the input 61. The resulting signal issupplied to the inputs 64 and 63 of the differentiation means 60 andaddition means 56, respectively. After differentiation in the means 60,the signal is supplied to the input 58 of the addition means 56 where itis added to the signal fed from the input 63. The amplitude and phase ofthe resulting signal are changed successively by the first orderaperiodic circuits 66 and 68. The signal is then further supplied fromthe aperiodic circuit 68 to the input 25 of the saturation unit 24. Thetime constants of the means 59 and 60 of the aperiodic circuits 66 and68 are selected to be different, while their transfer functions reanalogous to those described above.

During scanner adjustment described above, signals from respectiveoutputs (not shown) of the microprocessor 29 are supplied to the inputs83 (FIG. 13), 84, 85, and 86 of the correction circuit 54, that is torespective control inputs of the means 59 and 60 and aperiodic circuits66 and 68, and change their time constants. The phase shift is thusadjusted to a desired value.

When the desired phase shifts are small and when some operationalfrequency ranges are to be eliminated in scanners of FIGS. 1, 2, 3, 4,the signal from the transducer 19 is supplied to the inputs 74 and 75 ofthe differentiation means 70 and addition means 72 of the filter 69(FIG. 7). The signal is twice successively differentiated in the means70 and 71 and supplied to the input 73 of the means 72 where it is addedto the signal fed from the input 75. The resulting signal is deliveredto the input 77 of the first order aperiodic circuit 78. The amplitudeand phase of this signal are successively changed by the first orderaperiodic circuits 78 and 80. Then the signal is supplied from theaperiodic circuit 80 to the input 25 of the saturation unit 24. The timeconstants of the means 70 and 71 are selected to be equal to each other,while the time constants of the aperiodic circuits 78 and 80 should bedifferent from those.

When the phase shift of the scanner is adjusted as described above,signals from respective outputs (not shown) of the microprocessor 29 aresupplied to the inputs 87 (FIG. 14), 88, 89, and 90 of the filter 69,that is to respective control inputs of the means 70 and 71 andaperiodic circuits 78 and 80 are change their time constants. The phaseshift is thus adjusted to a desired value.

The operation of scanners for industrial laser machines of FIGS. 1, 2,3, 4 is described below for different embodiments of the phase shiftunit 21, when different application conditions are to be complied withby using different combinations of the phase shifter 45 (FIGS. 5 and12), correction circuit 54 (FIGS. 6 and 13), and filter 69 (FIGS. 7 and14) whose operation has been described already above.

The signal is applied to the input 22 (FIG. 8) and fed successively tothe phase shifter 45 and the correction circuit 54 of the phase shiftunit 21. The latter performs the phase shift of the signal in compliancewith the conditions described above in relation to the operation of thephase shifter 45 (FIGS. 5, 12) and the correction unit 54 (FIGS. 6, 13).The phase shift is adjusted by feeding signals from respective outputs(not shown) of the microprocessor 29 to the control inputs 81 (FIG.15),82, 83, 84, 85, and 86.

The signal applied to the input 22 (FIG. 9) is supplied successively tothe phase shifter 45 and filter 69 of the phase shift unit 21. Thelatter performs the phase shift of the signal on the conditionsdescribed above when dealing with the operation of the phase shifter 45(FIGS. 5, 12) and filter (FIGS. 7, 14). The phase shift is adjusted byfeeding signals from respective outputs (not shown) of themicroprocessor 29 to the control inputs 81 (FIG. 16), 82, 87, 88, 89,and 90.

The signal applied to the input 22 (FIG. 10) is supplied successively tothe correction circuit 54 and filter 69 of the phase shift unit 21. Thelatter shifts the phase of the signal on the conditions described abovein relation to the operation of the correction circuit 54 (FIGS. 6, 13)and filter 69 (FIGS. 7, 14). The phase shift is adjusted by feedingsignals from respective outputs (not shown) of the microprocessor 29 tothe control inputs 83 (FIG. 17), 84, 85, 86, 87, 88, 89, and 90.

The signal applied to the input 22 (FIG. 11) is supplied successively tothe phase shifter 45, the correction circuit 54, and the filter 69 ofthe phase shift unit 21. The latter shifts the phase of the signal onthe conditions described above when dealing with the operation of thephase shifter (FIGS. 5, 12), the correction circuit 54 (FIGS. 6, 13),and the filter 69 (FIGS. 7,14). The phase shift is effected by feedingsignals from respective outputs (not shown) of the microprocessor 29 tothe control inputs 81 (FIG. 18), 82, 83, 84, 85, 86, 87, 88, 89, and 90.

The scanner for industrial laser machines can also be equipped with ameans for inducing mechanical oscillations, making use of well knownelectrodynamic, magnetostriction, pneumatic, or hydraulic vibrationexciters.

This invention makes it possible to achieve optimal operationalconditions of the scanner without increasing its power consumption.

Besides, this invention provides an automatic device which eliminatesparticipation of an operator so that the scanner can be used inautomatic adjustable laser treatment systems in unmanned manufacturingenvironment.

Moreover, this invention provides a wider scanning frequency rangeextending both into the higher and lower scanning frequencies, and,also, a wider range of scanning amplitudes, which makes the field ofapplication of the scanner much broader.

Industrial Applicability

This invention can be employed for manufacturing durable precision unitsand machine components in various fields, such as aircraft industry,automotive tractor industry, and machine-tool industry. It can be usedfor automated hardening, welding, cutting, and surface heat treatment ofmetal workpieces.

In addition, this invention can be used in measurement technology basedon scanning, including instruments installed on mobile objects.

We claim:
 1. A scanner for industrial laser machines, comprising ahousing accomodating a movable scanning element, a means for inducingmechanical oscillations of the scanning element, which is mechanicallyconnected with the housing, at least two collision pairs, each pairhaving two components secured so that they can interact with each otherduring the movement of the scanning element, one component being securedon the scanning element and the other in the housing, characterized inthat it additionally comprises a measuring transducer (19) whichresponds to mechanical oscillations of the scanning element (4), a phaseshift unit (21) whose input (22) is connected to the measuringtransducer (19), a saturation unit (24) whose input (25) is connected toan output (23) of the phase shift unit (21), and a power amplifier (27)whose input is connected to the saturation unit (24) and whose output(28) is connected to the means (1,2) for inducing mechanicaloscillations of the scanning element (4).
 2. A scanner as claimed inclaim 1, characterized in that it also comprises a frequency meter (34)connected to the output (23) of the phase shift unit (21) and asaturation level control unit (36) connected to the frequency meter(34); the saturation unit (24) is provided with at least two controlinputs (40,41) connected to respective outputs (38, 39) of thesaturation level control unit (36).
 3. A scanner as claimed in claim 2,characterized in that the saturation level control unit (36) comprises adivision unit (91) having one input as an input (37) of the saturationlevel control unit (36) and the other input (92) connected to a constantvoltage source (93), an inverting direct-coupled amplifier (96) and anon-inverting direct-coupled amplifier (97), the input (94,95) of eachamplifier being connected to the output of the division unit (91), whilethe output of each amplifier is the respective output (40,41) of thesaturation level control unit (36).
 4. A scanner as claimed in claim 1,characterized in that it also comprises a periodic signal generator (42)having an output (43) joined with the output (26) of the saturation unit(24) and connected to the input of the power amplifier (27).
 5. Ascanner as claimed in any of the claims 1,2, or 4, characterized in thatthe phase shift unit (21) comprises a component selected from a groupincluding a phase shifter (45), a correction circuit (54), and a filter(69), in this order, individually or in combination.
 6. A scanner asclaimed in claim 5, characterized in that the phase shift unit (21)comprises a phase shifter (45) and a correction circuit (54) connectedin series to each other.
 7. A scanner as claimed in claim 5,characterized in that the phase shift unit (21) comprises a phaseshifter (45) and a filter (69) connected in series to each other.
 8. Ascanner as claimed in claim 5, characterized in that the phase shiftunit (21) comprises a correction circuit (54) and a filter (69)connected in series to each other.
 9. A scanner as claimed in claim 5,characterized in that the phase shift unit (21) comprises a phaseshifter (45), a correction circuit (54), and a filter (69) connected inseries to one another.
 10. A scanner as claimed in claim 1,characterized in that the phase shift unit (21) also comprises at leasttwo control inputs (32, 33), while the scanner additionally comprises aphase shift control means (29) having outputs (30,31) whose number isequal to that of control inputs (32, 33) of the phase shift unit (21),each said output being connected to respective input (32, 33) of thephase shift unit (21).
 11. A scanner as claimed in claim 5,characterized in that the phase shifter (45) has two control inputs (81,82), each said input being connected to respective output of the phaseshift control means (29).
 12. A scanner as claimed in claim 5,characterized in that the correction circuit (54) has four controlinputs (83, 84, 85, 86), each said input being connected to respectiveoutput of the phase shift control means (29).
 13. A scanner as claimedin claim 5, characterized in that the filter (69) has four controlinputs (87, 88, 89, 90), each said input being connected to respectiveoutput of the phase shift control means (29).
 14. A scanner as claimedin claim 10, characterized in that the phase shift control means (29) isa microprocessor.
 15. A scanner as claimed in claim 2, characterized inthat the phase shift unit (21) also comprises at least two controlinputs (32, 33), while the scanner additionally comprises a phase shiftcontrol means (29) having outputs (30, 31) whose number is equal to thatof control inputs (32, 33) of the phase shift unit (21), each saidoutput being connected to respective input (32, 33) of the phase shiftunit (21).
 16. A scanner as claimed in claim 3, characterized in thatthe phase shift unit (21) also comprises at least two control inputs(32, 33), while the scanner additionally comprises a phase shift controlmeans (29) having outputs (30, 31) whose number is equal to that ofcontrol inputs (32, 33) of the phase shift unit (21), each said outputbeing connected to respective input (32, 33) of the phase shift unit(21).
 17. A scanner as claimed in claim 4, characterized in that thephase shift unit (21) also comprises at least two control inputs (32,33), while the scanner additionally comprises a phase shift controlmeans (29) having outputs (30, 31) whose number is equal to that ofcontrol inputs (32, 33) of the phase shift unit (21), each said outputbeing connected to respective input (32, 33) of the phase shift unit(21).
 18. A scanner as claimed in claim 10, characterized in that thephase shifter (45) has two control inputs (81, 82), each said inputbeing connected to respective output of the phase shift control means(29).
 19. A scanner as claimed in claim 15, characterized in that thephase shifter (45) has two control inputs (81, 82), each said inputbeing connected to respective output of the phase shift control means(29).
 20. A scanner as claimed in claim 16, characterized in that thephase shifter (45) has two control inputs (81, 82), each said inputbeing connected to respective output of the phase shift control means(29).
 21. A scanner as claimed in claim 17, characterized in that thephase shifter (45) has two control inputs (81, 82), each said inputbeing connected to respective output of the phase shift control means(29).
 22. A scanner as claimed in claim 10, characterized in that thecorrection circuit (54) has four control inputs (83, 84, 85, 86), eachsaid input being connected to respective output of the phase shiftcontrol means (29).
 23. A scanner as claimed in claim 15, characterizedin that the correction circuit (54) has four control inputs (83, 84, 85,86), each said input being connected to respective output of the phaseshift control means (29).
 24. A scanner as claimed in claim 16,characterized in that the correction circuit (54) has four controlinputs (83, 84, 85, 86), each said input being connected to respectiveoutput of the phase shift control means (29).
 25. A scanner as claimedin claim 17, characterized in that the correction circuit (54) has fourcontrol inputs (83, 84, 85, 86), each said input being connected torespective output of the phase shift control means (29).
 26. A scanneras claimed in claim 10, characterized in that the filter (69) has fourcontrol inputs (87, 88, 89, 90), each said input being connected torespective output of the phase shift control means (29).
 27. A scanneras claimed in claim 15, characterized in that the filter (69) has fourcontrol inputs (87, 88, 89, 90), each said input being connected torespective output of the phase shift control means (29).
 28. A scanneras claimed in claim 16, characterized in that the filter (69) has fourcontrol inputs (87, 88, 89, 90), each said input being connected torespective output of the phase shift control means (29).
 29. A scanneras claimed in claim 17, characterized in that the filter (69) has fourcontrol inputs (87, 88, 89, 90), each said input being connected torespective output of the phase shift control means (29).
 30. A scanneras claimed in claim 10, characterized in that the phase shift controlmeans (29) is a microprocessor.
 31. A scanner as claimed in claim 15,characterized in that the phase shift control means (29) is amicroprocessor.
 32. A scanner as claimed in claim 16, characterized inthat the phase shift control means (29) is a microprocessor.
 33. Ascanner as claimed in claim 17, characterized in that the phase shiftcontrol means (29) is a microprocessor.